Cardiopulmonary exercise testing-derived circulatory power predicts major adverse cardiac events in adults with repaired tetralogy of Fallot.

Abstract

Background: Adults with repaired tetralogy of Fallot (rTOF) remain at increased risk for major adverse cardiac events (MACEs). Cardiopulmonary exercise testing (CPET) is increasingly used for risk stratification, though prognostic data beyond peak oxygen consumption (VO₂) are limited in this population. We evaluated the prognostic significance of CPET-derived variables for predicting MACE in adults with rTOF.

Methods: Clinical and CPET data from 47 adults with rTOF who underwent symptom-limited CPET were retrospectively analyzed. MACE was defined as cardiac-related hospitalization, device implantation, surgical intervention, or death. Associations between CPET variables and MACE were assessed using multivariable Cox regression adjusted for age, sex, and body mass index. Discriminative performance was evaluated using receiver operating characteristic (ROC) analysis.

Results: Over a mean follow-up of 20.8 months, 9 patients (19.1%) experienced MACE. Peak VO₂, oxygen uptake efficiency slope (OUES), and circulatory power (CircP) were significantly lower in patients with New York Heart Association functional class III and in those who developed MACE. CircP was positively associated with peak VO₂ (r = 0.899), OUES (r = 0.503), ventilatory anaerobic threshold (r = 0.537), and rate-pressure product (r = 0.673). On multivariable analysis, peak VO₂ (adjusted hazard ratio [aHR]: 0.80; P = 0.002), CircP (aHR: 0.99; P = 0.012), and OUES (aHR: 0.99; P = 0.015) were independently associated with MACE. ROC analysis demonstrated comparable discriminative performance among these variables, with CircP showing the highest sensitivity, specificity, and predictive values. Kaplan-Meier analyses confirmed significantly higher event rates below identified thresholds.

Conclusions: Peak VO₂, CircP, and OUES are significant predictors for adverse outcomes in adults with rTOF. CircP demonstrated relatively strong overall prognostic performance, supporting its potential role in clinical risk stratification. Larger studies are warranted to validate these findings.